Transducers for hard disk drives are conventionally formed in a slider, which has a disk-facing surface for interaction with the disk surface. During operation, the disk surface spins rapidly, typically at least several thousand revolutions per minute (RPM). Molecules of air that accompany the spinning disk surface form an air bearing that tends to lift the slider slightly from the spinning disk surface. The disk-facing surface of the slider is usually formed with an air-bearing surface (ABS) to control the lift characteristics. A known means for increasing signal resolution during both reading and writing of the transducer on the disk is to reduce the spacing between the transducer and the media.
The spacing between the transducer and media is typically the sum of several variables, including the spacing between the disk surface and the ABS, the thickness of any disk overcoat that protects the media, and any spacing between the transducer and the ABS. Conventional sliders are currently designed to "fly" at separations of less than a few microinches from a mean disk surface elevation. Roughness of the disk surface and the ABS are material factors in the spacing between the disk surface and the ABS, and minimization of roughness of these surfaces can decrease spacing between the transducer and the media and increase signal resolution.
Smooth disk and slider surfaces, however, tend to cause stiction when a slider is at rest on a disk. Mechanisms such as ramps for holding sliders away from the disk surface during nonoperation have been developed, but suffer from complexities and potential damage should the slider hit the disk surface. A conventional means for avoiding stiction involves forming a roughened portion of the disk surface for parking the slider on the disk. This unfortunately subtracts from the area of the disk that can be used for information storage. Roughening the slider ABS has also been proposed, but this increases the head-media spacing over the entire disk surface. Additionally, formation of the ABS typically occurs after the sensitive and delicate electromagnetic elements of the transducer have been formed, and so care must be taken in ABS formation not to damage those elements.
In U.S. Pat. No. 5,841,608, Kasamatsu et al. teach the advantages of etching the ABS to form a limited number of small projections that extend toward the disk. Due to a tilt of the slider during operation that raises the leading edge relative to the trailing edge, the projections are further removed from the disk surface than the trailing end of the ABS, so that spacing between the transducer and media is not increased. The slider is formed with much less crown and is held to the disk with a much lighter spring-load, reducing the tendency of the projections, which may be formed of various materials, to wear off or break free and leave harmful debris on the slider-disk interface. U.S. Pat. No. 5,768,055 to Tian et al., while much like Kasamatsu et al., stresses the importance of having an array of overcoat protrusions so that only the protrusions are in contact with the disk surface during nonoperation. Unfortunately, these protrusions also have a tendency to break free or suffer from excessive wear on the protrusion or protrusions that contact the disk surface.
An object of the present invention is to overcome the aforementioned difficulties in order to increase performance of information storage systems.